In a long-term evolution-advance (LTE-A) system, transmission nodes of low power are introduced on a basis of a conventional homogeneous network, so as to constitute a heterogeneous network, which includes a Macro cell, a Femto cell, a Pico cell, a remote radio head (RRH), and a relay.
In order to improve cell coverage and user's experience and increase throughput of an LTE-A system and a data transmission rate of a user, a coordinated multiple points (CoMP) technology has been introduced. Such a technology is to coordinate with a user in data transmission by using multiple geographically distributed transmission points, thereby improving performance of a cell-edge user and coverage of the cell, increasing throughput of the cell edge and the throughput of the system, and improving user's experience.
In the CoMP technology, different transmission points in a same cell may coordinate in transmission. FIG. 1 is a schematic diagram of coordination of different transmission points in the same cell in a CoMP system. As shown in FIG. 1, an eNB 101 and an RRH 102 in the same cell may coordinate to serve for user equipment 104, and the eNB 101 and an RRH 103 may coordinate to serve for user equipment 105.
Furthermore, different transmission points in different cells may coordinate in transmission. FIG. 2 is a schematic diagram of coordination of different transmission points in different cells in a CoMP system. As shown in FIG. 2, eNB/RRH 201 and eNB/RRH 202 in different cells may coordinate to serve for user equipment 203.
In order to select an optimal transmission point, a base station side needs to obtain information on a downlink from each transmission point to user equipment, usually including channel quality information (CQI), a precoding matrix index (PMI) and a rank, so as to select one or more optimal transmission points according to an optimization rule. In order to ensure backward compatibility and more flexible scheduling, the base station side needs have an ability of turning back to a single-point transmission of a conventional cellular network, which requires the user, in feeding back channel information, to report not only downlink channel information in CoMP transmission, but also downlink channel information in conventional single-point transmission.
Some heterogeneous network nodes different from a conventional cellular network are introduced into a heterogeneous network. Such heterogeneous network nodes, such a home eNodeB (HeNB), and a hot spot covered Pico cell, etc., use relatively low transmission power to cover a specific zone or user, with a relatively flexible manner of networking. If deployed reasonably, a user's experience will be increased to a relatively large extent. And in a Macro-Pico scenario, an almost blank subframe (ABS) is introduced into a standard for inter-cell enhanced interference coordination and interference cancellation (eICIC).
However, in the implementation of the embodiments of the present invention, the inventors found that only two measurement reference resource subsets are used in the existing channel state information feedback, and no individual channel state information feedback is configured for each cell or transmission point participated in coordination.
FIG. 3 is a schematic diagram of relationship between an ABS and a measurement subset in the relevant art. As shown in FIG. 3, one measurement subset (measurement subset 0) corresponds to an ABS, and another measurement subset (measurement subset 1) corresponds to a normal subframe.
Therefore, a unified structural design for feedback information is not used in the existing CoMP technologies, that is, channel feedback information for multiple transmission points or multiple cells cannot serve for not only transmission of a single cell but also transmission of multiple cells.
It should be noted that the above description of the background is merely provided for clear and complete explanation of the present invention and for easy understanding by those skilled in the art. And it should not be understood that the above technical solution is known to those skilled in the art as it is described in the background of the present invention.